Portland police believe people in two vehicles may have been shooting at each other Tuesday night, but authorities have made no headway in the case.

"We found numerous shell casings and people reported hearing engines revving and driving around fast," Lt. Robert King, a police bureau spokesman, said Thursday. "It may have been two people shooting at each other."

Several 9-1-1 callers reported hearing between three and 10 shots near the intersection of Northeast 18th Avenue and Rosa Parks Way just after 9 p.m. Officers searched the area and found the damaged car at the intersection.